Seasonality of Conceptions Under Varying Conditions in a Rhesus Macaque Breeding Colony

Abstract

Rhesus macaques (Macaca mulatta) are well documented as seasonal breeders. Despite this, little is known about what factors influence seasonal reproduction in rhesus. It has been proposed that rhesus are "relaxed income breeders" (Brockman and van Schaik, 2005), which means they respond to changes in photoperiod but endogenous cues can allow deviations from photoperiod-timed seasonality. This study presents the results of a natural experiment on the influence of different housing conditions (featuring different levels of environmental exposure) on the seasonal pattern of reproduction in rhesus. Once the number of attempts was controlled for, rhesus did not exhibit a seasonal distribution in their conceptions regardless of their level of exposure to environmental cues. This indicates that no conceptual model as of yet has adequately assessed the variation in seasonal reproduction in rhesus macaques.